1.1 welding q&a for students

7/11/2011
1
By  S K Mondal
Compiled by: S K Mondal                 Made Easy
IES 2010
Assertion (A): It is generally difficult to weld
Aluminum parts by normal arc welding process.
Reason (R): Hard and brittle Aluminum‐oxide film
is formed at the welded joints.
(a) Both A and R are individually true and R is the(a) Both A and R are individually true and R is the
correct explanation of A
(b) Both A and R are individually true but R is NOT the
(c) A is true but R is false
(d) A is false but R is true
Ans. (a)
IES‐2006
Assertion (A): Aluminium has poor weldability.
Reason (R): Aluminium has high thermal
conductivity and high affinity to oxygen.
(a) Both A and R are individually true and R is the (a) Both A and R are individually true and R is the
(b) Both A and R are individually true but R is not the
Ans. (a)
IES 2011
During plasma arc welding of aluminium, improved
removal of the surface oxide from the base metal is
obtained with typical polarity of :
(a) DC Straight
(b) DC reverse
(c) AC potential
(d) Reverse polarity of phase of AC potential
Ans. (c)
IES 2011
Consider the following statements.
Cast iron is difficult to weld, because of
1. Low ductility
2. Poor fusion
3. Tendency to crack on cooling
Which of these statements are correct ?
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1 and 3 only
Ans. (a) Compiled by: S K Mondal                 Made Easy
IES‐2006
Fabrication weldability test is used to determine
(a) Mechanical properties required for satisfactory
performance of welded joint
(b) Susceptibility of welded joint for cracking(b) Susceptibility of welded joint for cracking
(c) Suitability for joint design
(d) Appropriate machining process
Ans. (a)

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IES‐1999
The correct sequence of the given materials in
ascending order of their weldability is
(a) MS, copper, cast iron, aluminium
(b) Cast iron MS aluminium copper(b) Cast iron, MS, aluminium copper
(c) Copper, cast iron, MS, aluminium
(d) Aluminium, copper, cast iron, MS
Ans. (d)
IES 2010
Weldability of ferritic stainless steel used in
automotive exhaust system is improved by
selecting stainless steel electrode having low
content of
(a) Carbon (b) Nitrogen
(c) Chromium (d) Carbon and Nitrogen
Ans. (c)
IES 2010
Consider the following statements regarding
welded joints:
1. It is a permanent type of joint.
2. It is reliable and economical for pressure vessel
constructionconstruction.
3. It is free from fabricational residual stresses.
4. Such joints are suitable for static loading only.
5. Welding is a versatile and flexible metal joining process.
Which of the above statements are correct?
(a) 1, 2 and 3 only (b) 2, 3 and 4 only
(c) 1, 2, 3, 4 and 5 (d) 1, 2 and 5 only Ans. (d)Compiled by: S K Mondal                 Made Easy
IES 2010
The ratio between Oxygen and Acetylene
gases for neutral flame in gas welding is
(a) 2 : 1 (b) 1 : 2
(c) 1 : 1 (d) 4 : 1( ) ( ) 4
Ans. (c)
GATE‐1994
The ratio of acetylene to oxygen is
approximately………. for a neutral flames used in
gas welding.
( )(a) 1 : 1
(b) 1 : 2
(c) 1 : 3
(d) 1.5 : 1
Ans. (a)
GATE‐2003
In Oxyacetylene gas welding, temperature at the
inner cone of the flame is around
(a) 3500°C
(b) 3200°C (b) 3200 C
(c) 2900°C
(d) 2550°C
Ans. (b)

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IES 2010
Assertion (A): Oxidizing flame is used in gas
welding to join medium carbon steels having high
melting point.
Reason (R): In gas welding, oxidizing flame
produces the maximum temperature compared toproduces the maximum temperature compared to
neutral and reducing flame.
(a) Both A and R are individually true and R is the
(d) A is false but R is true Ans. (a)Compiled by: S K Mondal                 Made Easy
GATE‐2002
The temperature of a carburising flame in gas
welding is that of a neutral or an oxidising flame.
(a) Lower than
(b) Higher than(b) Higher than
(c) Equal to
(d) Unrelated to
Ans. (a)
IES‐2009
By which one of the following methods gray cast
iron is usually welded?
(a) TIG welding (b) MIG welding
(c) Gas welding (d) Arc welding(c) Gas welding (d) Arc welding
Ans. (c)
IES‐1998
In oxy‐acetylene gas welding, for complete
combustion, the volume of oxygen required per
unit of acetylene is
(a) 1( )
(b) 1.5
(c) 2
(d) 2.5
Ans. (a)
IAS 1994
In gas welding of mild steel using an oxy‐
acetylene flame. the total amount of acetylene
consumed was 10 litre. The oxygen consumption
from the cylinder is
(a) 5 litre
(b) 10 litre
(c) 15litre
(d) 20 litre
Ans. (b)
IAS‐1995
Assertion (A): If neutral flame is used in oxy‐
acetylene welding, both oxygen and acetylene
cylinders of same capacity will be emptied at the same
time.
Reason (R): Neutral flame uses equal amounts of
d loxygen and acetylene.
(a) Both A and R are individually true and R is the correct
explanation of A
Ans. (a)

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IES‐1992
The edge of a steel plate cut by oxygen cutting will
get hardened when the carbon content is
(a) Less than 0.1 percent
(b) Less than 0 3 percent(b) Less than 0.3 percent
(c) More than 0.3 percent
(d) Anywhere between 0.1 to 1.0 percent
Ans. (c)
IES 2007
Consider the following statements in respect of oxy‐
acetylene welding:
1. The joint is not heated to a state of fusion.
2. No pressure is used.
3 Oxygen is stored in steel cylinder at a pressure of 14 3. Oxygen is stored in steel cylinder at a pressure of 14
MPa.
4. When there is an excess of acetylene used, there is a
decided change in the appearance
of flame.
Which of the statements given above are correct?
(a)  1, 2 and 3 (b) 2, 3 and 4
(c) 1, 3 and 4 (d) 1, 2 and 4
Ans. (b)
IES‐2001
Oxyacetylene reducing flame is used while
carrying out the welding on
(a) Mild steel (b) High carbon steel
(c) Grey cast iron (d) Alloy steels(c) Grey cast iron (d) Alloy steels
Ans. (b)
IES‐1992
Thick steel plate cut with oxygen normally shows
signs of cracking. This tendency for cracking can
be minimised by
(a) Slow speed cutting( ) p g
(b) Cutting in two or more stages
(c) Preheating the plate
(d) Using oxy‐acetylene flame
Ans. (c)
IES‐2005
Consider the following statements:
1. In gas welding, the torch should be held at an angle of 30°
to 45° from the horizontal plane.
2. In gas welding, the Size of the torch depends upon the
h k f l b f dthickness of metal to be formed.
3. Drag in gas cutting is the time difference between heating
of the plate and starting the oxygen gas for cutting.
(a) 1, 2 and 3 (b) 1 and 2
(c) 2 and 3 (d) 1 and 3
Ans. (b)
Electric Arc Welding Electric Arc Welding

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JWM 2010
Assertion (A) : Bead is the metal added during
single pass of welding.
Reason (R) : Bead material is same as base metal.
(a) Both A and R are individually true and R is they
Ans. (a) Compiled by: S K Mondal                 Made Easy
GATE‐1993
In d.c. welding, the straight polarity (electrode
negative) results in
(a) Lower penetration
(b) Lower deposition rate  (b) Lower deposition rate
(c) Less heating of work piece
(d) Smaller weld pod
Ans. (b)
IES 2010
In arc welding, the arc length should be equal to
(a) 4.5 times the rod diameter
(b) 3 times the rod diameter
(c) 1.5 times the rod diameter
(d) Rod diameter
Ans. (d)
IES‐2005
1. In arc welding, 65% to 75% heat is generated at the anode.
2. Duty cycle in case of arc welding is the cycle of complete
welding of work piece from the beginning.
3. Arc blow is more common with DC welding.
(a) 1, 2 and 3 (b) 1 and 2
(c) 2 and 3 (d) 1 and 3
Ans. (d)
IES‐2001
In manual arc welding, the equipment should
have drooping characteristics in order to maintain
(a) Voltage constant when arc length changes
(b) Current constant when arc length changes(b) Current constant when arc length changes
(c) Temperature in the are constant
(d) Weld pool red‐hot
Ans. (b)
IES‐2001
In arc welding, d.c. reverse polarity is used to bear
greater advantage in
(a) Overhead welding
(b) Flat welding of lap joints(b) Flat welding of lap joints
(c) Edge welding
(d) Flat welding of butt joints
Ans. (a)

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IES‐1998
The voltage‐current characteristics of a dc
generator for arc welding is a straight line
between an open‐circuit voltage of 80 V and short‐
circuit current of 300 A. The generator settings for
maximum arc power will be
(a) 0 V and 150 A (b) 40 V and 300 A
(c) 40 V and 150 A (d) 80 V and 300 A
Ans. (c)
IAS‐1999
Open‐circuit voltage of 60 V and current of 160A
were the welding conditions for arc welding of a
certain class of steel strip of thickness 10 mm. For
arc welding of 5mm thick strip of the same steel,
the welding voltage and current would be
(a) 60 V and 80 A
(b) 120 V and 160 A
(c) 60 V and 40 A
(d) 120 V and 40 A
Ans. (a)
IAS‐1998
Assuming a straight line V‐I characteristics for a
dc welding generator, short circuit current as 400A
and open circuit voltage as 400 which one of the
following is the correct voltage and current setting
for maximum arc power?
(a) 400 A and 100 V (b) 200 A and 200 V
(c) 400 A and 50 V (d) 200 A and 50 V
Ans. (b)
GATE‐1994
The electrodes used in arc welding are coated.
This coating is not expected to
(a) Provide protective atmosphere to weld
(b) Stabilize the are(b) Stabilize the are
(c) Add alloying elements
(d) Prevents electrode from contamination
Ans. (d)
IES 2007
The coating material of an arc welding electrode
contains which of the following?
1. Deoxidising agent
2. Arc stabilizing agent
3. Slag forming agent
Select the correct answer using the code given below:
(a) 1, 2 and 3 (b) 1 and 2 only
(c) 2 and 3 only (d) 1 and 3 only
Ans. (a)
IES‐1997
Assertion (A): The electrodes of ac arc welding are
coated with sodium silicate, whereas electrodes used
for dc arc welding are coated with potassium silicate
binders.
Reason (R): Potassium has a lower ionization
i l h dipotential than sodium.
(a) Both A and R are individually true and R is the correct
explanation of A
Ans. (d)

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IES‐2002
Match List I with List II and select the correct answer:
List I (Ingredients) List II (Welding
functions)
A. Silica 1. Arc stabilizer
l dB. Potassium oxalate 2. De‐oxidizer
C. Ferro silicon 3. Fluxing agent
D. Cellulose 4. Gas forming material
Codes:A B C D A B C D
(a) 3 4 2 1 (b) 2 1 3 4
(c) 3 1 2 4 (d) 2 4 3 1
Ans. (c)
GATE‐2002, Conventional
The arc length‐voltage characteristic of a DC arc is given
by the equation: V = 24 + 4L, where V is voltage in volts
and L is arc length in mm. The static volt‐ampere
characteristic of the power source is approximated by a
straight line with a no load voltage of 80 V and a short
circuit current of 600A. Determine the optimum arc
length for maximum power.
Ans. 4 mm Compiled by: S K Mondal                 Made Easy
IES‐2001
Arc blow is more common in
(a) A.C. welding
(b) D.C. welding with straight polarity
(c) D C elding ith bare electrodes(c) D.C. welding with bare electrodes
(d) A.C. welding with bare electrodes
Ans. (c)
IES‐2001
Pinch effect in welding is the result of
(a) Expansion of gases in the arc
(b) Electromagnetic forces
(c) Electric force(c) Electric force
(d) Surface tension of the molten metal
Ans. (b)
GATE‐1992
A low carbon steel plate is to be welded by the manual
metal arc welding process using a linear V ‐ I
characteristic DC Power source. The following data are
available :
OCV of Power source = 62 V
Short circuit current = 130 A
Arc length, L = 4 mm
Traverse speed of welding = 15 cm/s
Efficiency of heat input = 85%
Voltage is given as V = 20 + 1.5 L
Calculate the heat input into the workprice Ans. 1668.5 JCompiled by: S K Mondal                 Made Easy
IES 2010
Assertion (A): Straight polarity is always
recommended for Carbon‐electrode welding.
Reason (R): Carbon arc is stable in straight polarity.
correct explanation of Acorrect explanation of A
Ans. (c)

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GATE 2011
Which one among the following welding processes
used non – consumable electrode?
(a) Gas metal arc welding
(b) Submerged arc welding
(c) Gas tungsten arc welding
(d) Flux coated arc welding
Ans. (c)
IES 2010
In an inert gas welding process, the commonly used
gas is
(a) Hydrogen
(b) Oxygen
( ) H li A(c) Helium or Argon
(d) Krypton
Ans. (c)
GATE‐2002
Which of the following arc welding processes does
not use consumable electrodes?
(a) GMAW
(b) GTAW(b) GTAW
(c) Submerged Arc Welding
(d) None of these
Ans. (b)
IES‐1994
Which one of the following welding processes
uses non‐ consumable electrodes?
(a) TIG welding
(b) MIG welding(b) MIG welding
(c) Manual arc welding
(d) Submerged arc welding
Ans. (a)
IES‐2000
Which one of the following statements is correct?
(a) No flux is used in gas welding of mild steel
(b) Borax is the commonly used flux coating on
welding electrodeswelding electrodes
(c) Laser beam welding employs a vacuum chamber
and thus avoids use of a shielding method
(d) AC can be used for GTAW process
Ans. (d)
IES 2007
In MIG welding, the metal is transferred into the
form of which one of the following?
(a) A fine spray of metal
(b) Molten drops(b) Molten drops
(c) Weld pool
(d) Molecules
Ans. (b)

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IES‐1997
MIG welding process uses
1.  Consumable electrode      2.non‐consumable electrode
3.  D.C. power supply 4. A.C. power supply3.  D.C. power supply 4. A.C. power supply
Of these statements
(a) 2 and 4 are correct
(b) 2 and 3 are correct
(c) 1 and 4 are correct
(d) 1 and 3 are correct
Ans. (d)
IES 2010
Assertion (A): Inert gas and bare electrode instead
of flux coated electrode is used in the case of
automatic TIG and MIG welding processes.
Reason (R): Better protection is provided by a cloud
of inert gas than the cover created by the flux.of inert gas than the cover created by the flux.
(d) A is false but R is true Ans. (b)
IES 2011
The welding process in which bare wire is used as
electrode, granular flux is used and the process is
characterized by its high speed welding, is known as:
(a) Shielded arc welding
(b) Plasma arc welding
(c) Submerged arc welding
(d) Gas metal arc welding
Ans. (c)
IES‐2006
In which of the following welding processes, flux
is used in the form of granules?
(a) AC arc welding
(b) Submerged arc welding(b) Submerged arc welding
(c) Argon arc welding
(d) DC arc welding
Ans. (b)
IES‐2005
Which of the following are the major
characteristics of submerged arc welding?
1. High welding speeds.
2. High deposition rates.
3. Low penetration.
4. Low cleanliness.
Select the correct answer using the code given below:
(a) 2 and 3 (b) 1, 2 and 3
(c) 3 and 4 (d) 1 and 2
Ans. (d)
IES‐2008
Assertion (A): Submerged arc welding is not
recommended for high carbon steels, tool steels,
aluminium, magnesium etc.
Reason (R): This is because of unavailability of
suitable fluxes, reactivity at high temperatures and
l bli ilow sublimation temperatures.
(a) Both A and R are true and R is the correct explanation
of A
(b) Both A and R are true but R is NOT the correct
explanation of A
Ans. (a)

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GATE‐1999
For butt ‐welding 40 mm thick steel plates, when
the expected quantity of such jobs is 5000 per
month over a period of 10 year, choose the best
suitable welding process out of the following
l bl lavailable alternatives.
(a) Submerged arc welding
(b) Oxy‐acetylene welding
(c) Electron beam welding
(d) MIG welding
Ans. (a)
IES‐2005
In atomic hydrogen welding, hydrogen acts as
(a) A heating agent
(b) One of the gases to generate the flame
( ) A ff ti hi ldi t ti th ld(c) An effective shielding gas protecting the weld
(d) A lubricant to increase the flow characteristics of
weld metal
Ans. (a)

1.1 welding q&a for students

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1.1 welding q&a for students